1. Technical Field
The present invention relates to a technique of tracking the movement of a target object in a moving image.
2. Related Art
Conventionally, a technique for tracking an object in a moving image has been utilized.
There is a tracking technique based on a color, as one of conventional object tracking techniques (Non-patent Document 1). In this technique, regions having similar colors in individual frames of a moving image are regarded as the same target object, and these similar-color regions are tracked over the frames, so that the location of the target object is tracked.
Moreover, there is another tracking technique based on a contour (Non-patent Document 2). In this technique, a contour model of a tracked target object is first created, and a contour similar to the contour model is searched for while the contour model is being slightly moved, so that the location of the tracked target object is tracked. This technique is based on the premise that the tracked target object is not moved broadly in a time interval.
Moreover, there is a tracking technique for tracking a contour shape with a particle filter, as another tracking technique based on a contour (Patent Document 1). In this technique, a contour line of a candidate whose shape is the same as that of a tracked target object is expressed by a single particle, and a plurality of particles are introduced as tracked candidates. Then, each particle is transited on the basis of a movement model, and a likelihood of the candidate contour line defined by each particle is observed after the transition, so that the location of the tracked target object is tracked.    Patent Document 1: Japanese Unexamined Patent Publication No. 2009-224924 (published on Oct. 1, 2009).    Non-patent Document 1: Katja Nummiaro et al., “An adaptive color-based particle filter”, Image and Vision Computing, Vol. 21, Issue. 1, pp. 99-110, 2003    Non-patent Document 2: Nikos Paragios and Rachid Deriche, “Geodesic active contours and level sets for the detection and tracking of moving objects”, IEEE Trans. PAMI, Vo. 22, Issue. 3, pp. 266-280